1. Field of the Invention
This invention relates in general to a refrigerant cycling device. More particularly, the present invention relates to a refrigerant cycling device whose high-pressure side possesses a hyper critical pressure.
2. Description of the Related Art
In a conventional refrigerant cycling device, e.g., a refrigerant cycling device equipped in an air conditioner, by switching a four-way valve (used as a flow passage switching means), the refrigerant discharged from the compressor passes goes through the four-way valve, and then gets discharged to an outdoor heat exchanger (a heat exchanger at the heat source side) during an air conditioning operation (a cooling operation). After the refrigerant radiates heat at the outdoor heat exchanger, the refrigerant is throttled by a depressurizing means to supply to an indoor heat exchanger (a heat exchanger at the user side) where the refrigerant evaporates. At this time, the refrigerant absorbs heat from the ambient environment to effectuate a cooling effect to cool the interior of the room. Thereafter, the refrigerant passes through the four-way valve and returns back to the compressor. The aforementioned cycle is repeatedly processed. On the other hand, the refrigerant discharged from the compressor passes through the four-way valve, and gets discharged to the indoor heat exchanger (a heat exchanger at the user side) during a heating operation. The refrigerant radiates heat at the indoor heat exchanger. At this time, the refrigerant radiates heat to the ambient environment to heat the interior of the room. Thereafter, the refrigerant is throttled by the depressurizing means and discharged to the outdoor heat exchanger (the heat exchanger at the heat source side). After the refrigerant absorbs heat from the ambient environment at the outdoor heat exchanger, the refrigerant goes through the four-way valve, and then returns back to the compressor. The aforementioned cycle is repeatedly processed.
In addition, for addressing the global environment issues in recent years, such refrigerant cycling device does not use the Freon type refrigerant, and a refrigerant cycling device, in which a natural refrigerant (e.g., carbon oxide, CO2) is used as the refrigerant, is developed.
When the high-pressure side is operated under a hyper critical pressure, it is generally known that the heating efficiency is obviously improved in a heating operation.
However, when the high-pressure side is operated under the hyper critical pressure, a coefficient of product (COP) in an air-conditioning operation is very worse. Therefore, for increasing the cooling capability, a large amount of refrigerant is required and that will cause a problem of increasing power consumption of the compressor, etc.